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