SQL Server takes far too much memory
Your question, at first, surprised me. Usually, I've seen memory issues with max server memory being configured incorrectly. But then I started pouring over the cumulative updates and realized that their are minefields of memory leaks sewn throughout all these cumulatives for SQL 2014! It's like Microsoft took a hint from their SQL 6.5-7.0 playbook and went retro on us.

Rather than spend hours of trouble-shooting, I would consider:

Option A:
Taking a snapshot of the VM and installing the latest cumulative 7 update for SQL 2014 sp2. And rolling back if necessary. (it looks like a memory leak related to SSAS is included in this update).

Option B:
Create a Microsoft support ticket to help yourself and the rest of us out by possibly adding a memory leak fix to cumulative 8 when it comes out. And updating your question based on Microsoft's findings.

Personally, I don't think I would consider any reason satisfactory for SQL Server going much above it's max memory limit--for any situation.