Once this limit is reached, you’ll see errors like the following, when trying to do anything in SharePoint.  I saw this error just trying to activate a feature.  You’ll also get errors when tying to check out files or import new files.

Could not allocate space for object ‘dbo.EventCache’.'EventCache_Id’ in database

Some solutions to work around this are to switch to SQL Server, which doesn’t have a file size limit, or to try to implement remote BLOB storage.  Getting the BLOBS out of SQL will significantly reduce the database size.  If the environment is just a test environment, you could also delete enough files out of the database or move files to a different database.