A few personal experiences on this topic, though none of them involve actual 'death' per se.

In my youth I would pop my neck using my hands, in a twisting & tilting motion. My chiropractor always advised me that this was foolish and extremely dangerous, but being the arrogant person that I am I ignored his warnings.

I did this for ~5 years with no problems whatsoever, and it always made me feel better when I did it.

One day I was with some friends at a large public arena type area for a seminar of one variety or another, and I popped my neck. This time rather than feeling good it hurt excruciatingly. I was completely unable to turn my neck to face left, nor tilt my right ear towards my right shoulder. I began to feel nauseous, like you do just before you puke. My friend said my face was turning white and my lips a blue/purple off color. I told him I was going to be sick and said I was going to go buy some water. I went to stand up, and it felt like gravity was many multiple times stronger than normal. Because of this added weight I collapsed immediately back into the chair I was sitting in.

I looked at my friend and asked him to get me some water. As I was looking at him only the area I was looking at was clear in my vision, the areas around began to blur dramatically. I heard a very deep buzzing sound, akin to what you hear after standing too close to speakers at a very loud concert. The buzzing began to drown out any other sounds, and the blurry / tunnel vision actually got to the point where my peripheral vision was purely black, not blurry at all.

Everything started spinning and I started seeing shapes and feeling an unusual numbness that was very uncomfortable. It's hard to explain feeling "numb" and "pain" at the same time, because it wasn't 'pain' but it made me feel discomfort like it was. The closest thing I can relate it to is the "dead arm" feeling you get when you hit your 'funny bone'.

This whole process took place over the course of about two minutes or three minutes at the most. A friend walked up to me and asked what was wrong, I looked up at him and felt a very unusual and indescribable "pop" in my neck. My vision and hearing cleared up within half a minute, and my normal muscle control came back within a few minutes after that.

I still wasn't able to move my neck however, so we immediately left and I saw my chiropractor. What he said was I had pinched a vein that runs through the vertebrae in your neck, and I was having a stroke. That chiro still uses my story to this day when lecturing his patients about not "self adjusting" as he calls it, as well as another story of some girls who tried popping one of their friends backs and made her a paraplegic as a result.

I have a few other stories to share on the topic, regarding being 'rabbit punched' while sparring (most agonizing experience of my life) as well as a hospital experience with carbon monoxide poisoning. Unfortunately I don't have the time to type it all out right now, but I'll come back and edit my answer within the next few days.