Baking soda & magnesium chloride reactions
It is difficult to reconstruct what actually happened based on a single picture.

Nevertheless, the essential effects seem to be the hygroscopy and deliquescence of magnesium chloride. Magnesium chloride has a strong affinity for moisture. When exposed to the atmosphere, the salt will absorb relatively large amounts of water from the air. Magnesium chloride can form several crystalline hydrates: $\ce{MgCl2.2H2O}$, $\ce{MgCl2.4H2O}$, $\ce{MgCl2.6H2O}$, $\ce{MgCl2.8H2O}$, and $\ce{MgCl2.12H2O}$. Furthermore, the salt absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a concentrated liquid solution.

Apparently, the concentrated liquid solution of magnesium chloride ran out of the glass vessel and formed a puddle on the dish drainer.