There's a series of limitations on peak motor torque. Motors usually hit the thermal limits first, but here are some of the other limits:
A big problem with older permanent magnet motors was that too much current could produce a field strong enough to demagnetize the magnets. Supposedly this is is less of an issue in the cobalt-neodymium magnet era, because the coercivity of those alloys is so high.
Then there's finding a pulsed current source to power the windings. Ultracapacitors are good for that.
Then there's finding big enough semiconductors to switch the thing. This, too, has become much easier. It's amazing how much current you can put through modern power MOSFETs.
Then there are mechanical limitations. At some point, something is going to bend from sheer torque. At some point below that, the windings will distort a little on each cycle and wear out.
Applications for this include railguns, catapults, and electrically launched rollercoasters. Interestingly, they're all linear motors.
(I haven't looked at this since the 1990s. The components needed are now far better and more available. Mostly as a spinoff of the electric car industry.)