The 14.04 version which is supported until 2019 still has the bug that it won't clear out old kernels after upgrading them. So if you don't look into your /boot partition now and then it fills up and breaks your installation.
Xe could hyperlink you to Dustin Kirkland's call for feedback here on Hacker News only a short while ago, where this subject came up several times. This is a well-known Ubuntu problem, and M. Kirkland xyrself said that taking purge-old-kernels out of the byobu package and putting it somewhere more obvious was a good idea.
Of course, this is an Ubuntu upgrade problem relating to Linux. It is specifically about kernel image files. So it has very little application to the Windows NT Linux Subsystem, which as we know uses the Windows NT kernel.
The 14.04 version which is supported until 2019 still has the bug that it won't clear out old kernels after upgrading them. So if you don't look into your /boot partition now and then it fills up and breaks your installation.