Occasionally, the client tries to guess the position of certain entities, for example boats. This causes effects such as boats crashing when they are actually 30 blocks away from land. I have not seen this happen for other entities, but I guess this bug affects other entities as well. I have seen this happen in 1.7.10 as well. I couldn't get any screenshots of it happening, because it only happens sometimes.
(If this is a duplicate, I searched but could not find any results.)
Boats desyncing are MC-2931