i think when there's a high heat capacity (Kj/K) that means the substance is being heat at lower rate, so you can use all kind of method to heat it up. Whereas when you have low heat capacity you would expect to raise the temperature higher at the faster rate and requires less energy, therefore the substance can be evaporate that mean you are not heating the substance but you are changing it's phases. I don't know if this crappy explaination is making any sense but i gave it a tried
