NASA astronaut Don Pettit is aboard the International Space Station. In his spare time, he devises experiments about whatever strikes his curiosity.
In this video, he produces a thin film of water on a loop, like we would use to blow bubbles here on Earth. He then demonstrates various properties of the water in space, plus adds some heat to produce nifty convection currents.
If you know the answer to the challenge question at the end, you can submit it on Physics Central.