How can someone change the salinity of water, without adding or removing salt?

I'm not as sure about this answer, but I think you can just boil it!

Explanation:

By boiling down any salt water, it lessens the salinity levels, and makes it more consumable and clean to drink. That's why they say to do that if you are on a deserted island and have no clean water!  

I hope that this was right and that it helps!

im not intirely sure but i think the anwser is d relative humidity