This is more of the rule than the exception in most languages that I know.
English is my fourth language, and when I started getting serious about speaking it properly, I realized two things:
- I had been pronouncing many words incorrectly, and to this day, 25 years later, I sometimes realize that I had the wrong pronunciation all along. Sometimes it is because I am familiar with the word in the original language, but it is pronounced differently in English, and sometimes it is because the pronunciation disobeys English rules.
- Many native speakers have no idea how to pronounce words that they have never heard.
But in Bulgarian, Russian, French, Spanish, Hungarian, Polish, German, there are very, very few words that you would mispronounce if you see them written down, as long as you know the applicable rules. Some of the languages above (not all) are also very easy to spell, because as long as you know the correct pronunciation, there is only one possible spelling.
Most of the languages have rythm and emphesis rules that you have to know, and are not written down. Getting that wrong is as confusing to a native speaker as choosing the wrong vowel sound in English.
Btw. The quick way to figuring out how close the writen and spoken languages are, is to check how old the written language is. If the written language is several hundred years old, then it is going to be rather different from the spoken language that has evolved faster in the meantime.