How do I disable the boot splash screen, and only show kernel and boot text instead?

Yes. Edit /etc/default/grub (using gksu gedit /etc/default/grub), and remove the "quiet splash" from the Linux command line:

Here's what it looks like by default:


Make it look like this:


After this run sudo update-grub2

Also from the GRUB menu, if you want to do this temporarily, you can hit E on a line to edit it, then Ctrl+X to boot the kernel line.

Make sure you don't have plymouth-theme-ubuntu-text package installed.