We usually think of materials changing state as a result of variations in temperature. Cool down water and it becomes ice. Heat up a piece of metal and it becomes molten metal. But pressure can also have a dramatic effect on some materials. Thixotropic non-drip paints change between gel form (a gel is a very malleable solid) and liquid when stirred. But the most dramatic and fun demonstration of the effect of pressure on state of matter is provided by custard.
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