Observations and results
The Ivory soap should have produced an impressive amount of foam compared with the Dial. Ivory has thousands of tiny air pockets in it—that's why it should have weighed less! These pockets of air expanded when they got hot, creating the soap bubbles that made up our foam.
But what caused the air to get so hot in the first place? As we discussed, microwave ovens are pretty bad at heating air. But part of our soap molecules are polar, so the microwave radiation caused these molecules to spin and build up kinetic energy, which created heat. This resulting heat was conducted from the melting soap to the air pockets, causing the pockets to expand and create some impressive foam.