Solution must be conductive, that means ions must be present. In most cases that means you need to dissolve some ionic substance. However, there are examples of non ionic substances that will do the same. Hydrochloride - as a gas - is not ionic, the bond is covalent, yet upon dissolution it becomes a strong electrolyte.
I am not sure I understand your question - yes, "changes phase" means "changes phase". I bet he means solid is no longer solid after dissolution, but if you mix ionic liquid with water there is no phase change.