The plane of quasi-elemental salt is the residue of the evaporation of Elemental Water. At its safest edge, it still seems to be only water bitter and unpalatable, but still water. Travel deeper into the plane and the water grows more laden with minerals. Crystals form, solidifying on even the smallest mote of a seed. Travelers who venture farther are in peril of becoming completely encrusted, the salts leaching all moisture out of their cells. Finally, all water is gone and there is only a solid mass of crystalline salts, hard and deadly, to block all progress. The solid salts end in a great cliff overlooking the plane of Negative Energy.
The plane of quasi-elemental salt represents the lack of water. Any beings who are partially or totally composed of water dehydrate rapidly while in the plane. The skin shrivels, the lips crack, the throat fills with dry choking, and the eyes - well, the eyes are the most horrible. Welcome to the plane of Salt.