Zài nà yīkè, tā méngfā le xué Zhōngwén de niàntou.
At that moment, the thought of learning Chinese sprouted in her mind.
Tips
usage
萌发 is used both literally (plants sprouting) and figuratively (ideas, feelings, desires emerging). The figurative use is more common in writing. Compare with 萌芽 (méngyá), which also means to sprout but is more often used as a noun.