The instructions below will help you do this without additional physical media: DVD or USB flash drive.
1. First of all, you should already have one of the OS Linux installed and running: Linux Mint/ Ubuntu or another.
2. You should have as well ISO image with the distribution you want to install.
3. Install the GRML-rescueboot program from the Software Manager or run the command in the terminal:
4. After installing GRUB-rescue boot, you can find an empty folder called grml (/boot/grml) by opening it as an root:
Or another file manager of your distribution.
sudo nemo /boot/grml
When the file manager with administrator rights opens, open the folder with the downloaded iso image and just copy the file to the grml folder.
An additional line should appear in the boot loader menu:
Note. People talking not all distributions can be installed in this way. I don't know why. Try and you will see!
May the Force be with you,