By Jutarat Skulpichetrat and Chaiwat Subprasom BANGKOK (Reuters) - Thailand's King Bhumibol Adulyadej left hospital on Monday to visit his Bangkok palace, his first such outing since he was admitted last year. King Bhumibol, the world's longest serving monarch, has been in hospital since May and has received treatment for multiple illnesses. Nervousness over his health and the succession has formed the backdrop to a decade of political crisis in Thailand, where the military took power in a coup in May 2014.