Video Demo: Expanding Soap

Ivory soap has air whipped into it during the manufacturing process, creating tiny holes with minuscule water droplets inside.  When microwaves hit the water, it vaporizes and expands it, causing the bar of Ivory soap to expand.  

Video Demo: Water Up!

This a favorite demo of mine that I have recently re-shot in HD.  It's a dramatic demonstration of how the rapid condensation of water can create a vacuum.