Easily boot an ISO image from GRUB2

Some time ago I've been reading about in a way that exists Boot an ISO image hosted on our hard drive from GRUB2. The truth is I never even try it, since I am terrible when dealing with GRUB. But I've read about a simple way to do so, using UNetbootin, And I decided to try and tell them that I was. I'll start by saying that to me it worked the first try. However, they should be cautious when