What do you do with hard sugar?

I got a 5 lb bag of white sugar out of storage and found it is solid all the way through. I know you can soften sugar in a microwave and tried that, but except for the paper packaging scorching a little, no effect. I can dissolve it in a large bowl of water, but then what would I do with it? It would feed a lot of hummingbirds, but I have seen nary a one. And you can stiffen old fashioned crocheted lace doilies in sugar solution. I haven’t seen one of those in ages. Any suggestions?