is it possible that the cranks will jerk because the back wheel slipped on a rock or something?

i notice it sometimes when i'm on the bike lane where there's lots of pebbles and it feels like the cog slipped momentarily.

if the cog and lockring looks and feels really really tight is it possible that it isnt? i took a lockring wrench to it (not the right size though but it still grabbed like two of the slots) and tried as hard as i could without stripping it (which was still alot of tourque) and it didn't budge one bit.