Tā tūránjiān xiǎngqǐ le shénme, zhuǎnshēn jiù zǒu.
He suddenly remembered something, turned around, and left.
Tips
usage
Slightly more vivid and dramatic than plain 突然. The 间 ('within/instant') adds a 'in that very moment' flavor - useful when you want to slow the reader down at the pivot of a story. 突然 is the safer everyday default.