It's not that strange and pretty common. Around 5% to 10% of men experience this and is called retrograde ejaculation and why this happens might have several reasons. Are you on medication? That could be a possible reason. If not, and it happens often or all the time, visit a doctor and they'll usually make an ultrasound and run some tests. No need to panic but get it checked if it persists. For more information, check https://www.healthymale.org.au/news/dry-orgasms