Idea to use electromagnetic radiation and its heating effects appeared in 1934 but it took some more modern technology and few more factors (like radar, chocolate and an inquisitive mind of one man) for it to be used properly. Read more about microwawe oven history.
Microwave oven is common kitchen appliance today but it was discovered by accident and at the beginning was so big and expensive that only hotels and rich could afford it. Read more about microwave oven history.
Induction cooker in an interesting type of stove that has its own benefits and limitations. Different types and designs of this kind of stove exist since the beginning of the 20th century but we had to wait until 21st for it to become widely available com common households.