Walking through blocks in realms

So I was in a realm when I jumped(in a 2 block tall space) and i went into the block above me. That happened whenever I go to a block that my head is supposed to hit. I can't just go through anything, only the block directly above me. When I'm inside, I just see the block texture. This has happened to me at least once in a real life day. I don't know how to trigger it, as it happens randomly. Also I was in creative mode.