What is Oobleck and why is it so mesmerizing to shoot? (VIDEO)

Oobleck is a mixture of cornstarch and water that forms a non-Newtonian fluid which kinda alternatively acts as a solid or a liquid  depending on how much force is applied to it.

The guys at The Backyard Scientist start off with some Oobleck tests with a chainsaw, then move on to hitting it with a pellet rifle and a golf ball cannon (which is pretty fly of its own accord) to get some neat results.