VIDEOS
Hele-Shaw cell experiments
Citric acid -> Baking soda
Bubbles are generated at the interface due to the reaction between citric acid and baking soda
Weicen Wang, Chunwei Zhang, Anindityo Patmonoaji, Yingxue Hu, Shintaro Matsushita, Tetsuya Suekane, and Yuichiro Nagatsu, Viscous fingering with gas generation with chemical reaction in a Hele-Shaw cell, Physics of Fluids 33, 093104 (2021) DOI: 10.1063/5.0062588
https://aip.scitation.org/doi/full/10.1063/5.0062588
Sesame oil -> Tooth paste
Tooth paste is a non-Newtonian.
Orange juice -> Worcestershire sauce
Pure viscous fingering that may taste awkward.
Borax -> Laundry starch
Fingering with Slime production. The mushroom-shaped explosions are repeated.
Vinegar -> Soy milk
Viscous fingering with yogurt production.
Bacteria colony instability?
See:
Yamaguchi and Suekane, Relationship between the shape of fingering by gel formation and diffusion phenomena in interfacial gel films
https://www.jstage.jst.go.jp/article/jsmeted/2020/0/2020_0016/_article/-char/ja/
Podgorski et al., Fingering instabilities of a reactive micellar interface, Phy. Rev. E, 76, 01622 (2007)
Ben-Jacob at al., Generic modelling of cooperative growth patterns in bacterial colonies, Nature, 368, 46-49 (1994)