Firstly this only works in survival. You need to take damage. For some reason, taking damage re-calibrates the server-client communication on where the client is. This means that standing on a ghost block will just increase your velocity (as you are falling) but as soon as you take fall damage, it will re-calibrate your location. Doing this on a slime block will just keep bouncing you up and up. Here is a video I made on it.

https://www.youtube.com/watch?v=PiHz4gVWnTQ

And here is a video on a practical use for it: https://www.youtube.com/watch?v=sFAlX7TKz1s

So yeah.
Thanks to Panda and Spire for helping me with the elevator.
I have known about this glitch for months, but I have been too lazy to do anything about it.