What should he do next in order to follow the steps of inquiry?

Since he wonders, then according to the formal, methodical procedures of scientific inquiry, he should not go running off and trying stuff before he forms a hypothesis that can be tested.

In his mind, at some point, he should say to himself "Self !  It seems to me that if salt is added to water, it makes the water boil at a higher temperature than pure water does."

And only THEN, with this statement in mind, he's ready to design an experiment to test it.

multiple

none, its a machine