Our results are:

For citric acid, the crystals were dry, had a flat surface, it had small bubbles due to the gas in the mixture.

For Epsom salt, the crystals

looked like shredded glass, the crystals were rectangular, and the surface of the dish was slimy.

For Kosher salt, the crystals had an X-like marking in the middle of the crystals; it smelled and tasted salty; and in the surface of the dish, the center was small bits of crunched up salt.