Thanks to TV show Brainiac we can get a very dramatic demonstration of how custard changes state under pressure.
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.
Click the image to watch the video.