Nothing. They're terrestrial.
the salt starts to disintegrate
It dies.
It floats.
explodes
nothing
Water dissolve and transport salt.
Your feet get wet.
The concentration of salt increase up to saturation.
The color of the flame depends on the metal from the salt.
It lowers the boiling point, and makes it "salt water".
It happens because if you put a certain amount of salt in a cup with water the more salt you put in the more things you put in will float.
Salt cannot be "put in mercury" unless the salt is mechanically restrained. Mercury has a much higher density than salt and does not chemically react with it, so that salt will simply float on the mercury.