No, this is really not true. It's so odd how tenacious these "facts" are when just putting them in context shows how they couldn't possibly be true (let alone actually trying them out).

Simple syrups have a ratio of sugar to water much higher than a coke, and if you try one directly, you'll find it just tasting sweet. Or just eat some sugar or a sugar cube, which has a totally insane concentration of sugar.

You certainly won't be in any danger of vomiting.