Hooking or catching and edges is caused when a ski is rolled onto the edge without any pressure applied. Instead of having a ski flex and carve an arc, the edge engages the snow and goes in the opposite direction than desired, generally causing a fall depending on the amount of engagement.
On old straight skis this was caused mostly by front tip, modern shaped skis equally by tip or tail.
The solution old days was a detune to prevent this pressure/roll timing issue. Modern skis we base bevel which allows some roll before pressure is applied. Greater base bevel is a more forgiving tune at the sacrifice of performance. Between both methods base bevel has less negative impact than a detune of yesteryear.
If you hook or catch an edge, you let the ski, ski you vs you skiing the ski. Race skis are very punishing because of stiffness and tune, quickly showing those that have sloppy timing between applying pressure (or lack there of) and rolling onto the edge. The punishment quick and pain in a face plant or torn ACL (any Front edge vs Rear inside edge).
Final note, not much of a roll from flat is required without proper pressure to cause improper engagement which leads into an edge feel and balance discussion for prevention (way better than tuning for prevention).