Change grahical Ubuntu boot splash into text mode

gedit /etc/default/grub

Find the word "quiet splash".
Remove the word "quiet splash".

Save the file.

Update the grub.

update-grub

How to change boot splash in to text mode

You can change Ubuntu traditional graphical boot splash into text mode. See the following commands,

gedit /etc/default/grub

Find the following line,

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

Delete the words "quiet splash" . See the modified line below,

GRUB_CMDLINE_LINUX_DEFAULT=""

Then update the Grub,

sudo update-grub