Why burn a candle next to a glass of water?

Burning a candle next to a glass of water can create a visually interesting effect and serve a practical purpose. The heat from the candle melts the wax and produces vapor, while the flame consumes oxygen, leading to a decrease in air pressure inside the glass. If the flame goes out, the cooling air inside the glass creates a vacuum that can draw water up into the glass, demonstrating principles of air pressure and atmospheric science. This simple experiment can be a fun way to explore concepts in physics and chemistry.