A Candle That Sucks Water
Place a candle upright in the middle of a saucer. Fill the saucer with water. Light the candle. Place a glass over the candle. When the flame goes out, the water in the saucer will get sucked into the glass.
How Does It Work?
When the candle is burning inside the glass, the heat makes the air expand, so some of the air escapes outside the glass. The candle goes out after it uses up all the oxygen, so the air inside the glass cools. As it cools, the pressure inside the glass drops. Some of the carbon dioxide formed by the flame dissolves in the water as well, decreasing the pressure even more. The water outside the glass on the saucer is forced into the glass by the higher aire pressure outside.