Installation hangs on splash screen without indication what happened. Maybe it really working slowly on something and one should wait, maybe it is dead and something should be changed to make installation possible...
quiet splash from the boot options (f6 to edit them).
So once one reached this screen:
press F6 and remove
quiet splash from command that will be displayed below
(Thanks to leszek from https://webchat.freenode.net/?channels=lubuntu for this answer!)