The first experiment I did today was very simple. I boiled water in a pot, and then watched the pot lid clatter. It was lifted by the expanding water. Below, you can see a video of it.
My second experiment was a little more complicated, but it turned out very good.
First, I brought some water to a boil in a teapot. After it was steaming, I held a water bottle over the opening. When some steam collected in the bottle, I then put it upside-down in a pot of cold water. When the steam condensed, the water filled the bottle part way. (Note: normally, the air inside the bottle will keep the water out. However, if you fill the bottle with steam, it creates a vacuum, sucking some water in. See diving bell.)
You can see some pictures below.
