Comment 6 for bug 1510731

Have you tried with Ubuntu rather than Kubuntu? If not, you might want to try with Ubuntu, just to rule out whether this is a Kubuntu specific issue.

Using the “something else” option presented during installation of Ubuntu 15.10 and Ubuntu 16.04 (onto a non-UEFI system with a gpt formatted drive), I have been able to create a LUKS-encrypted volume on sda2, and I have been able to install boot (/boot) into non-encrypted sda1, and root (/) into LUKS-encrypted sda2.

I have noticed, however, that, after creating the LUKS-encrypted volume on sda2 (using the create the next partition as "physical volume for encryption" that you mention), I sometimes have to wait a bit (sometimes a minute or more) before "sda2_crypt" (or something like that, I don't recall the exact label) is created, into which I can install root. Maybe your installation hangs t this point?

Although the above works for me, I have NOT been able to install boot (/boot) into non-encrypted sda1, root (/) into LUKS-encrypted sda2, and home (/home) into into LUKS-encrypted sda3. Rather, although I am able to create all of the LUKS-encrypted volumes, the installer hangs during installation when the following is displayed:

“Creating ext4 system for /home in partition #1 of Encrypted volume (sda3_crypt)...”

See https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1523194 for the issue that I'm describing.