Thanks all for the input. After reading a few replies, in my mind's
eye, I visualized a sheet of steam forming and breaking, almost
instantaneously, on the bottom of the pot.

I drained a bottle of beer, broke the bottle, and placed the bottom
in the pot.

That works. I can hear the bottle bottom rattling as the lye boils.

Nucleation. What would we do without it?

~D