Is it possible to install Ubuntu FROM a smartphone?

It is perfectly possible. You can carry multiple live CD images on your phone all the time and use them when needed, but you will need root access to your phone for that. There is an Android app called DriveDroid. DriveDroid allows you to boot your PC from ISO/IMG files stored on your phone. This is ideal for trying Linux distributions without the need to burn different CDs or USB flash drives.

Alternatively, if your phone has mass storage emulation (Android 4 usually has NOT) AND your PC supports UEFI, then, in theory, you can place rootfs and UEFI boot partition on that emulated storage. In theory.