What happens if you leave Salt and vinegar together overnight?

Answer 1

Not much really happens.

The salt (sodium chloride) dissociates into sodium ions and chloride ions in solution.

The vinegar (acetic acid) dissociates into hydrogen ions (protons) and acetate ions in solution.

The solid salt will most often dissolve in the vinegar. But, that's about it.

Now, if you have something like a metal in the salt and vinegar solution, the chloride ions can induce nucleophilic attack on the metal ions, resulting in corrosion of the metal.

If you boiled away the water in the solution, you would be left with some proportion of sodium chloride (salt), anhydrous acetic acid, and sodium acetate.

Answer 2

It became salted vinegar