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Why is phosphorus(V) oxide used as a drying agent?

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Phosphorus(V) oxide, also known as tetraphosphorus decaoxide ( $P_{4} O_{10}$ ), is used extensively as a drying agent because of its great affinity for water.1

When exposed to moisture, it reacts vigorously with water to form orthophosphoric acid, a process that liberates heat:1

$P_{4} O_{10} + 6 H_{2} O \to 4 H_{3} P O_{4}$

Because of this strong dehydrating capability, it is widely employed in chemical analysis to remove water from various compounds and to dry gases.12