This could all be rubbish - but...
When accelerating your boat up onto the plane, once you have got there, you can throttle back slightly and stay on the plane.
This is because a hull just before it planes - or as it comes up onto the plane - has more drag than the same boat on the plane (which is the whole point
- as well as being able to go faster).
SO...going the other way, if you are just on the plane, and throttle back just enough to drop off the plane - as you decelerate your drag increases rapidly as you begin to displace (and speed decays), but your prop/engine will still be trying to go faster. Water is incompressible (pretty much), so the only place for it to go is up.
Sound reasonable? Or a load of old cobblers?