Remove moisture from bucket of salt?

I have a 40+ lbs bucket of aquarium salt that I use to mix up batches of saltwater for my water changes (as most everyone does around here I'm sure). Well, unfortunately, I left the bucket uncapped for a day or two in my not-completely-dry basement and now I have a bunch of hardened chunks in the bucket and it's making it tough to measure out salt properly. Does anyone have any tips or tricks to remove the moisture from inside the bucket? Thanks in advance!