It's interesting to see the paver bricks turning into glass and boiling up like molten lava.
Glass in the molten state is conductive to electricity, and it's how large glass bottle making plants produce liquid glass.
I worked with a guy, that had that as his first EE job, had a story how the kiln refractory developed a leak that dumped the molten load. They had to use chipping hammers to remove the mess.