Today I was playing the arcade1up version of this game. On the first level I used the jump+attack powerful attack. I killed the first foot soldier then I killed the remaining 2 foot soldiers with this same attack. I was Michaelangelo and before it hit the ground my sprite seemed to clip above the ground and I was immediately taken to the boss fight
There is a feature in the 1up cabs that allow you to trigger the level end when you press all three buttons together. It may have been this, but usually it triggers the end of the level, not the boss fight - do you have a video of this? Could be some kind of wrong warp.
edit: after conversing with an owner of a 1up cab, it seems this is just the normal skip behavior as it skips to the next room, which would have been the boss room.
