The sound of the consonant <em>c </em>is a good example of this.
Explanation:
The letter <em>c</em> is not always pronounced the same in Spanish. When it is followed by the vowels <em>a, o </em>or <em>u</em>, the letter <em>c </em>has the same sound as the letter <em>k. </em>
A few words with this hard <em>c </em>sound are:
la cama
el coro
la cucaracha
When it is followed by the vowels <em>e </em>or <em>i, </em>it has the same sound as the <em>s </em>or <em>th</em> in Spain and Equatorial Guinea.