it could be a few different things...
a warped disc, seized or sticky piston in the caliper/drum, or the brake hose may have worn and collasped inside.
what condition are the hoses in? is stiffness constant or is it only at one point when you rotate the wheel?
Usually if the pads are gone you'll get a rasping of the metal backing on the disc/drum. This can cause unwanted heat and possibly even warp the disc/drum.
If the hoses are old/worn looking (cracked rubber) i would replace them while your there, as its cheap and easy to do but requires bleeding the system so youl need fluid too, but for the peace of mind its worth it.
if you change the pads and hoses and its still there its most likely a sticky piston in the caliper/drum and if your disc brakes you will need a refurb (kits cost £14 for two wheels) there was a good article on this in camper and bus last month. For drum brakes this is slightly more expensive