What you need:
What to do:
1. Blow up one balloon. Knot it so that its air doesn't escape.
2. Light the candle.
3. Hold the balloon above the candle and then lower it slowly, closer to the flame
4. Fill the second un-inflated balloon with a little water. Then blow it up with air. Knot off the end.
5. Hold the water-filled balloon over the flame. Allow the flame to touch the balloon so that the water-holding area is just above it.
The first balloon which was filled with just air popped even before it touched the flame. Just being close to the heat melted the rubber. The second balloon didn't pop. A black dot materialised on the surface of the balloon where it was in contact with the flame.
The only difference between both balloons is the presence of water. Water is good at soaking up heat. As the flame burns below balloon, the water closest to the flame gets heated and rises up. Cooler water replaces it and stays there until it gets hot and rises. Thus, the water keeps taking the heat away from the rubber of the balloon. The cycle continues until the heat exceeds the waters capacity to absorb it. Only then will the balloon pop. The black dot formed on the balloon's surface is nothing but soc left by the candle flame.
Picture Credit : Google