What is the reaction between Magnesium chloride and Sodium bicarbonate?
Having actually perform this reaction, I can say with certainty that when you mix aqueous sodium bicarbonate with aqueous magnesium chloride, there is no apparent reaction. This is consistent with an equilibrium reaction (actually, just ions): 

$$\ce{2 NaHCO3 + MgCl2 &lt;=&gt; 2 NaCl + Mg(HCO3)2}$$

However, upon brief heating in a microwave (for example), a white precipitate of magnesium carbonate develops indicating the reaction has moved to the right. 

$$\ce{2 NaHCO3 + MgCl2 -&gt;[Heat] 2 NaCl + MgCO3(s) + CO2 (g) + H2O}$$