Booting iso files in Ubuntu

This can be achieved by following some instruction from this page.

But what I found to be extremely easy is to use grml-rescueboot.

What you do is:

sudo apt-get install grml-rescueboot

and after that you copy the iso files into /boot/grml
Once you copied/moved the files in the location you run the following command:

sudo update-grub

Reboot and choose what live iso you want to try.