What does "crackle , pop" mean when used on the Internet?

[ashling]

When Kellogg's* Rice Krispies are toasted the cooked and dried rice "berries" expand their size (puff) to many times their normal size. Since the weight of the rice berry and its material mass remains nearly the same, the rice material is stretched to form very thin walls of the Rice Krispies structure. This is much like a very thin glass crystal. When subjected to a change in heat, a severe "stress" is set up and the thin wall fractures - creating a Snap, Crackle and Pop!

This happens in the cereal bowl when cold milk (i.e. heat stress) is poured in the Rice Krispies and presto SNAP! CRACKLE! POP! The sounds are made by the uneven absorption of milk by the cereal bubbles.