This option is particularly useful to see the bootsequence or to enter the password of an encrypted harddrive during the boot process. Edit the /etc/default/grub file:

sudo vi /etc/dafault/grub

And change the value “quiet splash” of GRUB_CMDLINE_LINUX_DEFAULT with “”.

if you use vi use the two following commands:

:%s/GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"/GRUB_CMDLINE_LINUX_DEFAULT=""/
:wq

After that update grub:

update-grub2