Cannot find the files filling up my /var partition

I'm running a python application that keeps crashing with

.OperationalError: database or disk is full

, even though I have 300G in the partition where this is installed and from where I'm running it. However, I noticed my

/var

partition is being filled and emptied while the application is running, and that it is 90% full. I saw this with System Monitor. Turns out that when I see the partitions with Baobab, I see only 6G available of 50G in that partition. However... $ sudo du -sh /var/ 8.4G /var/ I simply cannot see the files/directories saturating my

/var

directory, Any ideas what could be happening?