MSSQL Server 2014 Freezes every time RAM get's to 79GB

We have the Enterprise version 12.0.2000 running on:
Windows 2012 R2 Standard 64 Bit
8x16GB Micron 16GB DDR4 2Rx4 (128 GB of RAM)
2.6GHz Intel Xeon-Haswell (E5-2690-V3-DodecaCore)
2.6GHz Intel Xeon-Haswell (E5-2690-V3-DodecaCore)

The Issue that we have:
Around the same time each day for the past 4 days 1 hour up and down the SQL Server becomes completely unresponsive, we are not able to connect to it at all, we can RDP into the machine and watch what's happening but we can not connect to the SQL Server, since it happened 4 times the first two times it lasted for 20 minutes the third time it was 10 and today it was 30 minutes. RAM starts to drop at that point and after it drops to 0 everything is back to normal.

What's interesting
The RAM almost always get's to almost 80GB which you can see in the attached Usage.png screenshot and one of the...