What you need:

• a batch of iced cupcakes
• popping candy
• a glass of water

What to do:

1. Bake or borrow a batch of cupcakes for morning tea.
2. Just before eating, sprinkle liberally with popping candy
3. Think of the science while experiencing the explosions of joy**

**Joy in this case is a synonym for pressurised CO₂ gas. Actual joy may or may not occur.

What’s happening?

Popping candy gets its ‘pop’ by setting bubbles of high-pressure CO₂ gas inside the candy. After the candy sets, the crystallised sugar keeps the gas safely sealed in. However, as soon as your saliva starts to dissolve the candy, the walls holding in the bubbles get thinner and eventually they can’t withstand the high pressure, and the CO₂ gas explodes out to let the pressure equalise.

This is why it is important to only put the candy on when serving morning tea – any earlier and the candy can soften a little due to humidity or moisture from the icing, allowing all the gas to escape before the fun happens.

You can actually see the bubbles of gas escaping if you put a couple of rocks of candy in a glass of water.