The few times I do siphon into a bucket (to catch potential fry/shrimp that got accidentally hoovered), I place the hose onto a chair (or something similar) next to the bucket, hose end pointed downward into the bucket, so this doesn't happenI once started siphoning and realized the hose had slipped out of the bucket while I was pumping water.
Most times, I'm siphoning into my garden or flower beds, though...old tank water = highly nutritious for plants