[abdullahkhalids]

Yes. Though the disappearing doesn't happen when you eject the removable media. When you first boot from the removable media, the OS loads itself into the RAM. If you want to open additional programs, then those are loaded from the media into RAM and then executed. However, you can remove the media at any point after boot, and after that you only run the programs that are already loaded into RAM.

Also we have had live images of various OSes for many decades. I seem to recall that we used to load DOS from floppy disks.