The "tombstone phenomenon" occurs due to one of the left and right electrodes of the chip rising off the substrate as a result of an imbalance of tension applied to the electrodes during soldering. The magnitude of the tension imbalance is affected by the area of the left and right lands, the amount of solder used, the temperature, random variations in mounting position, and so on. The key to proper mounting of the component lies in the minimization of this imbalance.
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