Popping noise coming from rear brake drum

About a week ago I noticed a grinding noise coming from my tire while I was driving. Crazy thing was when I hit the brakes it stopped so i'm sure the brakes aren't the problem. Then, about 2 days ago I drove to store as well as the grinding noise I heard like a popping noise as the tire turned. I was told it could be wheel or hub bearings. I'm no mechanic so i'm not sure but I need to know so I can get it fixed. Someone please help!