How pop-corn pops

On the messenger one day, I was discussing corn food with a friend. He suddenly asked me about scientific phenomena behind the popping of a corn. I was a bit poetic that day, so here is my instant reply to him (within 45 seconds):

Pop-corn endosperm has moisture inside
And the kernel, in size, is not that wide
The pericarp is impervious to moisture,
And we expose the corn to high temprature.

The water boils inside the grain
But steam’s escape-efforts go in vain
The pressure inside builds to 10 atmospheres,
And the corn pops, a sound one hears.

The explosion turns the kernel inside out,
And this popcorn, we put in mouth!