Acid/alkali + salt reaction?
Hydrochloric acid solutions can only readily reach about $\pu{40\%}$ concentration. So say you add $\ce{NaCl}$ to $\pu{98\%}$ sulfuric acid. You quickly end up supersaturated with respect to dissolved $\ce{HCl}$ and it goes into the gas phase which thus limits the ability for that reaction to go in the reverse direction.  

The situation is similar for the second reaction, except in this case rather than removing carbonate from the system via volatilization, you are forming the insoluble $\ce{CaCO3}$, preventing the reaction from happening in the reverse direction.