Using OmniDiskSweeper (as suggested in other answers), the culprit for me was GarageBandGarageBand. The download of Essential Sounds said "2.1 GB", yet the size on disk was 24 GB and likely going to 50 GB (because I paused the download at 1.2 GB for lack of disk space). That explains why my disk space kept growing even as I purged more of it.
$ cd /private/var/folders/q8/n9hvxyg92c98xmp5bqsxyrr80000gn/C/com.apple.garageband10/com.apple.MusicApps/audiocontentdownload.apple.com $ du -sh lp10_ms3_content_2016/ 24G lp10_ms3_content_2016/
I also found out that Homebrew keeps the download of installed versions:
Note downloads for any installed formulae will still not be deleted. If you want to delete those too:
rm -rf $(brew --cache)
Thanks for the answer. What's the use of keeping already installed formulae downloads files around?
In case something goes wrong and you have to reinstall.
I had the Glasgow Haskell compiler ghc
installed for unknown reasons. Removing it freed another 3 GB, 1.5 GB for the cached download and 1.5GB for the binary files (in ~/Library/Caches/Homebrew/downloads
and /usr/local/Cellar/
respectively).