In this chapter, God unleashes three more plagues through Moses, the plagues of livestock death, boils and fierce storms.
Something I didn't mention before is that all of these chapters are characterized by the LORD speaking to Moses. This form of manifestation runs parallel with the plagues, and continues afterwards as the LORD has quite a bit to say in this book. This particular verbosity is strongly contrasted to the relatively mute appearance of the LORD in Genesis, where God would only say a very few (but important) things. In Exodus, he appears to be interested in saying quite a bit, in almost every chapter.
This chapter begins with the LORD telling Moses to tell Pharaoh that another plague is about to strike, again hitting at the Egyptian economy by destroying all of their livestock. As with the plague of flies, this one specifically states that the Hebrews, located in Goshen, would not be afflicted by the plague. Already we can see the escalating force of the plagues. This plague is striking against the domesticated animals, part of the Genesis 1 enumeration of creatures.
Next is a plague of boils, which signifies the complete defeat of the magicians who can no longer even stand before Moses because of the painful boils they are suffering. This plague would not strike at the economy, but strikes at the physical well-being of the Egyptians, much like the prior plagues of gnats and flies, which did little to damage their wealth and much to harm their physical health. This plague shows the LORD's dominion over the sky realm, when Moses throws soot into the air which "will become fine dust over all the land," a symbolic act in Pharaoh's sight that unleashes the fury of the plague.
This is not the first symbolic act: before this, Moses had Aaron strike the water of the Nile in the sight of Pharaoh to unleash the plague of blood. The purpose, of course, is to warn Pharaoh that the plagues are not random accidents of nature but are specifically and directly related to the power of the Hebrew God, the LORD.
As if all this were not enough, the LORD continues to proclaim more plagues against the Egyptians. After a while the list of plagues starts to get brutally repetitive, where it seems like the LORD is just listing off pestilences and curses to strike his enemies. I suppose this is why the LORD hardened Pharaoh's heart, because otherwise I don't know how anyone could stand against this kind of power. The next plague is a "very heavy hail" with an accompanying storm of lightning and rain. There are a few things interesting about this plague. For one, it strikes down trees and plants, showing dominion over yet another type of creation from Genesis 1. For another, it also states that it did not strike in the land of Goshen "where the sons of Israel were." And lastly, this time Moses gave a very specific warning to the Egyptians, that they must bring their livestock and servants in from the fields. (On a related note, I have no idea where the livestock came from, since they were just wiped out two plagues ago. There is possibly an unspecified gap of time between the plagues, because here it does not say that they occurred from one day to the next. There could have been a more lengthy gap of time between plagues here, allowing the Egyptians to rebuild their flocks.) This warning is interesting because it's the first time we've seen the possibility of the Egyptians taking direct action to avoid the consequences of a plague: before this, they would all be afflicted regardless of what they did or thought, but now the LORD is giving them an opportunity to demonstrate by action that they regarded his warning.
One wonders how any of Pharaoh's servants could have doubted the words of Moses by now, given that they've already suffered under 6 plagues. This possibly makes the (hypothetical) gap in time between plagues more important, because maybe it has been some days or weeks or possibly even months since the last plague, and maybe they are starting to forget it and disdain the words of Moses again. It would certainly be a consistent attitude with Pharaoh, who regards the word of Moses very highly during a plague and then promptly changes his mind once it is removed.
Pharaoh's response is even more humbled than what we see before, as here he not only agrees to let the Israelites go, but calls his own behavior "wicked." So there is clearly some impact happening, but all the same, Pharaoh reneges again.
Verse 31 shows us that the destruction was not total. The hail ruins all of the crops which had sprouted, but that was only two of the four major crops: flax and barley. As the LORD explains in verses 15 and 16, the purpose of the plagues is not to destroy Egypt, it is to demonstrate the LORD's sovereignty over natural creation and his superiority over the false idols of Egypt.