Any soluble salts present on the surface will dissolve in the water.

I was wondering if you had any suggestions about how to tell exactly when the salt dissolves?

As long as the salt does not dissolve in water, it is pretty harmless to most materials.

Stir until the salt dissolves, then add the rice vinegar and four cups of cold water.

For example, salt dissolves in water but not in alcohol.

So this article you read - what evidence did it offer to claim that salt does not dissolve in water?

This is why salt dissolves so well in water.

The more salt dissolved in the water, the easier it is for things to float.

The second part of the lab they were supposed to see if salt and sugar would dissolve in vegetable oil.

Many require salts or particular ions to dissolve in water.