If you drink an instant damage potion while on low enought HP to die, you will respawn with an empty bottle, and the full instant damage potion will be laying where you died

I wasn't able to recreate it, so it might have been due to server lag (because, the first time it happened was on a multiplayer server)

edit: I remembered I was recording it for fun https://youtu.be/yFNedE7xJ_k (and i added subtitles, because I doubt you understand polish) (and we made only three potions (if you want, i have a half an hour long video that is not edited and has the whole potion making process shown (sorry, but i don't think i'm gonna be able to add subtitles to that)))