There is insufficient system memory in resource pool default to run this query
While this probably isn't an exact answer to your problem I'll post it anyway hoping it may help you in a way.

What you are seeing is not the MEMORYCLERK_SQLBUFFERPOOL but the MEMORYCLERK_SQLLOGPOOL taking up all the memory.

There is a known issue with SQL 2012 SQL Server 2012 experiences out-of-memory errors. Even though you are running 2014 there is a chance that you are running into the same issue (even though I couldn't find a connect item for 2014).

There is also this known issue for both 2014 and 2012 involving index rebuilds and always on. You didn't specify you are using that but maybe the same bug has other triggers: FIX: SQL Cache Memory decreases and CPU usage increases when you rebuild an index for a table in SQL Server

So my best suggestion for now is to update to the latest CU and see if it still happens, since there have been a few fixes around MEMORYCLERK_SQLLOGPOOL recently. Since you are running RTM with 2 security fixes only that could make sense, there is an SP1 + multiple CU's available.

Since there is also fairly high memory usage in MEMORYCLERK_XTP used by in-memory OLTP this article may help you troubleshoot: Monitor and Troubleshoot Memory Usage