I had a pronunciation problem, and I didn't know exactly what to do about it, so I figured the best solution would be practice, pronunciation practice, and more pronunciation practice until the problem was resolved.
I was teaching a pronunciation class to a small group of ESL students from various Asian and South American countries, and everything was going well until we began to practice our pronunciation of specific vowels and consonants.
One of the students from South Korea struggled to pronounce the vowel sound found in the word "law" or "pause." At first, I reassured the student that this was nothing to worry about and that in time he would get a handle on that particular sound, but he wanted to keep trying and practice pronouncing the sound. I helped him, but we didn't get too far.
During one class, however, I overheard this student having a conversation about the upcoming holiday break and I distinctly heard him say "Santa Claus" with perfect pronunciation, though some of the words on either side were a little indistinct.
I immediately asked him to repeat what he had said, and to my amazement he once again said "Santa Claus" perfectly. Then I asked him to say "law," one of the words we had previously struggled with. However, when he said the word "law," he mangled it just as he had before. Then I had him say the word "claw," and he mispronounced that as well.
After several repetitions of his being able to say "Santa Claus" perfectly well, but unable to pronounce any other words with the "awww" sound, I began to push harder, thinking (or not thinking, really) that further repetition would remedy the problem.
It didn't, but it did create a strain between myself and this ESL student, and it took some time to get our teacher-student connection back on track.
I never figured out why he couldn't pronounce this particular sound outside the simple example of Santa Claus, but I did learn that in the big picture of his learning English, this one sound really did not matter all that much.