An explosion means the tire blew off the rim - occasionally the tire will re-seat afterwards, but a cut or puncture will not explode.

Almost certainly you had a bit of tube pinched under the tire bead, and this is easy to do right at the valve, that's why you should push the valve up inside the tire to make sure it's free before you inflate. Not likely that the nut itself was the problem, but possibly the issue would've fixed itself if you didn't have the nut on.