What Causes the ‘Pop’ of a Popcorn Kernel?

A popcorn kernel pops because steam inside it turns into gas and pushes the shell apart like a tiny balloon.

Imagine you have a tiny hard shell, that’s the outside of the popcorn kernel. Inside, there’s water and starch, like a little pot with soup. When you heat up the kernel, the water inside starts to boil, creating steam.

As more steam is made, it gets trapped inside the kernel. Eventually, the pressure from all that steam becomes too much for the shell to handle, just like a balloon bursting. The shell suddenly cracks open, and the starch turns into fluffy white stuff we know as popcorn!

It’s like when you fill up a balloon with air until it pops, only this time, instead of just air, it's steam turning into gas that makes everything go fluffy and light.