Pic4: pasta broth (ravioli) - 2016-11-13
Pic6: cassava soup with sago pearls
Pic5+6 borrowed from the internet
The cooking liquids from grains and many tuber vegetables are very rich in starch. These often-overlooked broths have a a fairly delicate, yet defining flavor. Just think of the popularity of noodle soup!
Noodles, tapioca and pasta are sometimes added to other soups to enhance them, but we often cook rice, potatoes, pasta etc. by themselves as well. Rather than literally pouring the cooking liquid down the drain every time, drink it instead; or use it to enrich soup and sauce recipes.
See also: Potato Egg Drop Soup and Ravioli Soup.