So a while back, me and my friend were playing minecraft when we constructed our first nether portal. We decided take it in turns to go in, so I went in first. When he entered the nether portal though, I saw his nametag and his skin wedged into the obsidian. He said that he was stuck on the loading screen and all he could hear was him taking damage, he died and lost all of his items and since we weren't playing a realm we didn't have a backup.

This has also happened to me a couple times, but haven't died.