Our kitchen has been the scene of many a vinegar-powered volcano, but here via Boing Boing is something even more wet, wild, and bewildering.
Cornstarch mixed with water has very spooky properties. It is a suspension that seems to transition back and forth between liquid and solid, depending on kinds of forces applied to it. If you try this at home, do not, do not, do NOT pour the mess down a sink or toilet once you have finished playing. The cornstarch will in time settle out of the liquid water, becoming a solid and very expensive mass in the pipes for your plumber to deal with.