I pumped up my rear tire and was careful not to overinflate it. In fact, I only pump up to around 50psi, even though the max is about 80. After about a minute after inflating it, it went BOOM. Now that I've had a chance to change the tube, I was surprised to find where the tube ruptured. The rupture was about a 6 inch long area on the rim-facing side of the tube.

I was expecting it might be on the sidewall-facing side, indicating the tube was not properly in the tire and was caught between the tire and rim. Or maybe the tire-facing side, indicating a sharp object embedded in the tire. I just replaced the rim tape a year ago with Velox. I checked it and it seems fine. So I replaced the blown inner tube with a new one, pumped it up, and all seems fine so far. Haven't ridden it yet.

Any ideas what could have caused the tube to explode like that? I've never seen (or heard) it happen before.