You are presented with the quiz "What is left over when salty water is heated?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "heating salt water causes the water to evaporate while the salt remains" and "for example, in salt water, salt is the solute and water is the solvent". 

So, what's the best answer to the question?


 

        The solute   